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Topics - pocock

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There are some hints about multi-seat setups in other topics in the forum

Multi-seat can make the workstations more viable because the cost is shared between two or three users.

I had some discussions about this with a few people.  Most people are satisfied that POWER9 provides enough compute capacity but there were some practical concerns

The type of user who would benefit from this setup is typically a developer, system administrator or IT support worker who already works in Linux

By their nature, this type of user would like to tweak the system, for example, installing some kernel module, installing some non-standard version of some development header files or whatever.

What level of isolation can be achieved between users in such scenarios?

For example, using virtualization, people can have their own kernels and separate GPU ports.

Using LXC and cgroups, people can have their own root filesystem but they share a kernel

Has anybody tested these possibilities with POWER / Linux workstations or even on x86?

I found some links about the topic for some of the distributions that people are using

Hardware passthrough in LXC or running a desktop in a cgroup

two X servers one graphics card

Debian - Multi Seat

Fedora - Multi Seat

Arch - Multi Seat

FreeBSD - Multi Seat

Has anybody tried any of these cards with a recent kernel?

Does the kernel command line option mentioned on the wiki here make any difference?

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General Discussion / Areca Tri-mode HBA NVMe / SAS / SATA controllers
« on: October 17, 2021, 05:41:43 am »

Online store / catalog

These are not cheap but they look like interesting HBAs for people who have a lot of disks and want to link them all into their workstation or server through a single x16 slot.

Has anybody tried any of them?

How do they compare to other brands offering a Tri-mode solution?


Quattro 400 web page

Has anybody tried it?

It is not really fast enough for somebody who wants the newest SSDs like the Samsung Pro 980, each of those can do 7GB/s.

For previous generation SSDs operating up to 4GB/s this looks like an interesting HBA for software RAID, Btrfs or ZFS in a x8 slot.


OWC Shuttle - four SSDs, 3.5"

OWC Shuttle - one SSD, 2.5"

ZD Net pictures

The model that takes four SSDs may be more interesting for Talos II and Blackbird users

It is part of OWC's set of products for Thunderbolt but it says you can use the Shuttle by itself in any workstation that has U.2 support from a HBA.

Being more verbose, the full system comprises three parts: OWC's external Thunderbolt-to-PCIe case, an SSD carrier module, like a miniature backplane that goes in the case and finally, the Shuttle module itself.  This full system would not be relevant for Talos II / Blackbird as they don't have Thunderbolt ports, nonetheless, the Shuttle by itself may be interesting.

It is not clear how the four M.2 SSDs are combined into a single U.2 port: is this bifurcation, is there some kind of switch chipset or is there something else in the U.2 standard that allows multiple devices to be combined into a single U.2 port?

It says that they support PCIe 4.0 but it is not clear if they support the newest high speed PCIe 4.0 SSDs.


Official site

Specifications in PDF

This is a controller for multiple SSDs.  It uses a switch, not bifurcation.  As noted elsewhere, bifurcation is not really supported on Talos II

The specifications and price look interesting for workstation builds where you want to combine 2, 3 or 4 SSDs for a simple RAID-1 mirror with the Linux md RAID, btrfs or ZFS.

The benefit of buying this type of card is that only one PCIe slot is consumed for multiple SSDs.  On the systems with only two slots (Talos II Lite and Blackbird) that is an important consideration.

Specifications in PDF give a lot of detail about support for backplanes, it is not clear if you can simply connect the ports directly to U.2 SSDs using the right cable.

The M.2 SSDs can be mounted in U.2/M.2 carriers.

Has anybody tried it?

The wiki has a lot of details about how to install firmware but I couldn't see instructions about how to check the currently running firmware version.

Furthermore, Raptor appear to be using "System Package" version numbers to represent some mix of individual packages that have their own distinct version numbers.  For example, the Talos II v2.00 isn't OpenBMC 2.00.  I feel this list would look better as a table showing the Raptor version in one column and other relevant versions in extra columns.  For example, a column for OpenBMC, another for Linux kernel, etc.

Then if you log in and look at the uname output you can take the kernel version and try to deduce which System Package from Raptor you are running.

Does anybody know about support for Firefox WebAssembly (WASM) on ppc64le?

Some web sites like Zoom don't work without it.

Since March, it looks like Jitsi Meet may require WebAssembly too

Is WASM available in any recent version of Firefox?  Can it be enabled if I rebuild Firefox from source?


I took the download of Eclipse for ppc64el and tried it on my system.

It crashes at startup, I opened a bug report with full details, download link, stack trace

Does it work for anybody else?

To test it:

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mkdir ~/eclipse-test
cd ~/eclipse-test
wget ''
tar xzf eclipse-SDK-4.19-linux-gtk-ppc64le.tar.gz


It looks like retailers are building combined Ryzen + RX 6800 XT systems with OEM parts and you have to buy the whole system instead of buying the GPU alone.

Has anybody else noticed this trend or been able to get the GPU standalone for a POWER9 system?

Applications and Porting / Zoom - errors about audio, video not supported
« on: February 16, 2021, 04:21:51 pm »

Zoom has test site at

It always gives an error "Your browser does not support using the computer's audio device"

Looking at the JavaScript web console, there are some messages like this

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Uncaught TypeError: i.a.sendSocket is not a function
    Lodash 3

One person suggested bugs with slow download of resources but I'm on gigabit fibre.  An x86 laptop on the same fibre connection does not give the problem.  This issue could be a red herring.

Both laptop and Talos II are running Firefox 78.7 ESR

One difference I notice: the Talos II always shows the captcha, the laptop always bypasses the captcha

Does anybody have any insights into this or workarounds?

Will a newer Firefox build fix it?

I built a backport of the latest version of Jami for various architectures including ppc64le.  This is one of several ways to do chat and VoIP with no central server, more details on the official web site

These are distributed through the Debify repository

If you didn't use Debify already, you can add the repository with this command:

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$ wget -O - | bash

and then you can get the latest Jami with:

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sudo apt update
sudo apt install -t debify-buster-backports jami

and then launch it with this command:

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$ jami-gnone

I had some communication with the Blender and ffmpeg developers about issues with transparency

For example, the preview panel in Blender was corrupted and some input images or videos were corrupted in OBS

The root cause was in ffmpeg, it is fixed here.  The issue is also tracked in Blender.

I produced an updated version of my Debian backport of ffmpeg 4.3.1, it now includes both the POWER9 optimizations and the fix for this particular issue.  The version with the fix is ffmpeg_4.3.1-5~bpo10+2

If you already used packages from then you can simply do

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apt install -t debify-buster-backports ffmpeg

If you did not already use it, you need to add the apt source before installing/upgrading your ffmpeg:

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$ wget -O - | bash
apt install -t debify-buster-backports ffmpeg

We had some discussions in fedora-devel about changing the default page size from 64k back to 4k

This could be done for Fedora 34 - I opened a change request under Fedora policy

How do people feel about this?

Does anybody want to take ownership of the Fedora change request?

Technically, only one line of code needs to change but there is some coordination to make sure everything in userland is rebuilt and to do some tests of the installer as a bare minimum.

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I might be willing to take ownership of the change personally but if somebody else wants to take ownership, that will free up some of my time for other things.

It is also important to verify that other users are comfortable with this strategy: please feel free to comment through the Fedora mailing list.

As promised, the packaged version of the kernel is now available for people who want to test the 4k page size.  There is another thread tracking problems related to the 64k page size, in other words, reasons you might want to try the kernel here with 4k

Debian kernel packaging tools allow me to build multiple flavours of the kernel as separate packages and you can install all of them concurrently.  Therefore, you can install the default kernel with 64k page size and also the kernel with 4k page size at the same time.  When you boot, the grub menu will let you choose between these different kernels.

If you didn't already use any of the packages from the Debify repository then you need to enable the repository with this command:

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$ wget -O - | bash

After enabling the repository, you can get the new kernel with these two apt commands:

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$ sudo apt update
$ sudo apt install -t debify-buster-backports linux-image-powerpc64le-4k
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following additional packages will be installed:
Suggested packages:
  linux-doc-5.9 debian-kernel-handbook mkvmlinuz
The following NEW packages will be installed:
  linux-image-5.9.0-0.bpo.2-powerpc64le-4k linux-image-powerpc64le-4k
0 upgraded, 2 newly installed, 0 to remove and 10 not upgraded.
Need to get 40.3 MB of archives.
After this operation, 240 MB of additional disk space will be used.
Do you want to continue? [Y/n]

Please share any feedback about using the package

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